Charging base



FIG. 1 is a perspective view showing a front, top and left side for a charging base of our new design;

FIG. 2 is an elevational view of a right side thereof;

FIG. 3 is an elevational view of a rear side thereof;

FIG. 4 is a plan view of a bottom side thereof; and,

FIG. 5 is a plan view of a top side thereof.

The broken line matter in all figures is for illustrative purposes only and forms no part of the claimed design. 

The ornamental design for a charging base, as shown and described. 